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UNITED STATES PATENT OFFICE.

GEORGE H. MILLS, OF EAST BOSTON, MASSACHUSETTS.

PUMP.

Specification of Letters Patent No. 28,439, dated May 22, 1860.

To all 'to/1,0m it may concern:

Be it kno-wn that I, GEORGE H. MILLS, of East Boston, in the county ofSuffolk and State of Massachusetts, have invented a new and usefulImprovement in Pumps; and I do hereby declare that the following is afull, clear, and exact description of the same, reference being had tothe accompanying drawings, forming part of this specification, in which-Figure l, is a longitudinal elevation of a steam pump with myimprovement exhibiting the principal parts in section. Fig. 2, is a planof the same.

Similar letters of reference indicate corresponding parts in the twofigures.

To enable others skilled in the art to make and use my invention I willproceed to describe its construction and operation.

A, represents the inner stationary cylinder of the pump to which thepiston or plunger B, is fitted in the usual manner, said cylinder beingclosed at its ends by heads a', c', the latter of which is constructedwith a stuffing box Z), for the piston rod c, to work through. Thiscylinder A, is made much longer than the cylinder of an ordinary pumpthat is to say much longer than the stroke of the piston, added to thethickness of the piston and has its exterior turned up perfectlycylindrical and concentric with its bore.

C, is the outer stationary cylinder portions of which near the endsthereof are bored truly of a uniform size somewhat larger than theexterior of the inner cylinder, and the middle portion of which is madesomewhat larger than the said truly bored portions as shown at CZ, d,(Fig. l) to constitute the suction chamber to the bottom of which isconnected the suction pipe D, and on the top of which is the vacuumchamber E. Annular cavities e, e, are cast in the said outer cylinder O,outside of the truly bored end portions thereof to constitute twodischarge chambers which are both connected with the same air vessel F,which covers the vacuum chamber E. The said outer cylinder C, is boltedto a bed plate G. The inner cylinder A, is secured within the outercylinder in a position concentric and parallel thereunto by means of thehead a, at one end and two rods f, 7", at the other end. The truly boredend portions of the outer cylinder C, are provided with two series ofports g, g, and g, g', extending nearly all around it and leading fromits interior to the two discharge chambers c, e, and the inner cylinderis provided with a precisely similar series of ports 7L, 71., and h',7L', arranged exactly opposite to g, g, and g', g. The inner cylinder A,is also provided with two series of ports 2'., 2', and i', extendingnearly all around it, the outer edges of said ports being opposite tothe ends of the suction chamber (l, cl, that is formed within the outercvlinder.

H, is the intermediate cylinder bored out to fit snugly but easily tothe exterior of the inner cylinder A, and having its exterior turnedconcentrically with its bore to lit snugly but easily within the boredend portions of the outer cylinder C. This intermediate cylinder isprovided with two series of ports m, m, and m', m', of similar form tog, g, g', g', and z', z', z, f', so constructed and arranged around it,g, 72 m, and g, h', and m, being also properly arranged, so that whilethose m, m, register with z', i, those m', m', register with g, g', andIt', 7L', as shown in Fig. l, and that, while those m m', register withc, c", those m, m register with g, g, and 71.. One end of theintermediate cylinder H, passes through a stuffing box 7s, la, in oneend of the outer cylinder O, and the corresponding end of theintermediate cylinder is fitted with a stuffing box .7', around thecylinder. The piston rod c, which also constitutes the piston rod of thesteam cylinder I, which is furnished with a cross head L, which works onparallel guides Z, l, which connect the pump cylinder with the steamcylinder I, and the said cross head is connected by rods n, n, withcranks 0, 0, on a shaftJ, on which there are also two eccentrics p, p,whose rods g, g, are connected with lugs r, r, on the intermediatecylinder II, of the pump for giving the said cylinder its reciprocatingmotion. The cranks o, 0, control the length of the reciprocatingmovement of the piston B, which should be such that it just covers theports z', z', and z", i', of the inner cylinder as it terminates in oneand the other direction. The length of stroke of the intermediatecylinder produced by the eccentrics p, p, is just suiiicient to open itsports m, m, to the outlet ports g, g, It, 71 and the inlet ports z', z',alternately and to open its ports m', m, to the outlet ports g', g',7L', h', and the inlet ports z, z", alternately, the said ports in theintermediate cylinder always IOO The eccentrics p', p, are arranged 90Oin advance of the cranks 0, o, and hence the ports commence to open atthe commencement of the stroke of the piston and are Wide open When thepiston is at the middle of its stroke. in which condition it isrepresented in Fig. l, the ports m, form a communication between theinner cylinder andthe suction chamber behind the piston, andy the Water`enters the inner cylinder by the ports z', z', and at the same time theports m', m, form a communication between the ports g', g, and L, h, andthe Water is discharged from the inn-er cylinder in front of the pistoninto the discharge chamber. As the piston moves in the oppositedirection the Water enters the inner cylinder by the ports c, z, andleaves it by g, and h.

The intermediate' cylinder H, having a positive action relatively to theplunger As the piston is moving to the left lcauses the opening andclosing of the kports inder H, in combination With the tWo Sta- 35tionary cylinders A, C, and piston B, as and for the purpose hereinshown and described.

GEORGE H. MILLS.

Witnesses:

CHAS. H. COFFIN, GEO. W. WAirT.

